Harry w



I (No M94161.)

" v H. W. LAWRENCE.

. I RHEOSTAT.

. 110,482,093. I I Paten ted Sept. v6 1892;

we m "w m 7 6 H 1 3 5g ATTORNEY.

- UNITED STATES PATENT Onricn.

HARRY WV. LAWRENCE, OF DENVER, COLORADO, ASSIGNOR OF ONEJIALF 'lOllENRYH. METOALF, OF SAME PLACE.

RHEOSTAT.

SPECIFICATION forming part of Letters Patent No. 482,093, datedSeptember 6, 1892. Application filed A ril 25, 1891. Renewed January28,1892. Serial No. 418,997- No model-l To all whom it may concern:

Be it known that I, HARRY W. LAWRENCE, a citizen of the United States ofAmerica, residing at Denver, in the county of Arapahoe and State ofColorado, have invented certain new and useful Improvements inRheostats;

- marked thereon, which form a part of this specification.

My invention relates to an improved rheostat or means for controllingincandescent;-

lamps.

The device is located within the circuit of the lamps designed to becontrolled thereby and is capable of such adjustment that the briiliancyof the lamps may be regulated at wil The improved device consists of themechanism illustrated in the accompanying drawings, wherein Figure 1 isa side elevation of the device; Fig. 2, atop or plan View thereof; Fig.3, a bot tom or underneath view Fig. 4,a section on the line a: m, Fig.1; and Fig. 5, an enlarged detail of an adjustable clamp for securingthe resistance material .in place.

In the views let the reference-numeral 1 designate a block composed ofinsulating material, through the center of which passes a metal stem'2,provided with an insulating but ton or knob. 3. At the bottom of plate 1stem 2 is passed through a stationary metal arm a and secured in placeby a nut 5 and is designed to be rotated by.taking hold of button 3. Toa screw 6, passing through arm l, is attached one of the circuit-wires7. Secured to stem 2 and adapted to engage the upper sur face of block 1is an arm 8. The outer extremity of this arm engages small metal blocksor plates 9, secured to block 1 byscrews 10, passing through the block,the heads being located underneath. Plates 9 are distinct and separatefrom one another and form either a circle or an arc of a circle aroundstem 2..

Supported upon plate 1 and extending around the stem 2 on the outside ofplates 9 and forming either a circle or are thereof, as

may be desired, is a section 12, of carbon or other suitable resistancematerial, preferably circular in cross-section. The carbon 12 isconnected with screws 10, and therefore with plates 9, by wires 13,extending from the head of the screws up through the blockl to clampsl4, surrounding the carbon, and secured at the top by screws 25. It willthus be seen that these clamps may be adj usted to correspend with thecondition of the carbon with reference to the change produced therein bya difference in temperature producing enpansion and contraction. Each.wire 13 is distinct and separate from every other wire 13.

As before stated, one circuit-wire 7 leads to or is connected with arm4, secured to stem 2. The other circuit-wire 15 is connected with thehead of a screw 10, located atone extremity of the are in which thescrews are arranged. Now it will be seen that the circuit in which thelamp to be controlled lies is completed from wire 7 through arm 4, stem2, arm 8, plate 9, and screw 10 to the other wire 15, provided the lampis turned clear on and the current does not have to pass through anyportion of the carbon 12, which is the case when the outer extremity ofarm a is directly above the screw 10, with which wire 15 is electricallyconnected. \Vhen, however, it is desired to turn down the lamp orregulate the brilliancy, stem 2 is turned to the left over plates J oraway from the screw 10, with which wire 15 is connected, thus compellingthe current to travel through a greater or less resistance, according tothe strength of light required. It will thus be seen that the light maybe nicely regulated and controlled by my improved device. The last plate9 to the left, or the one farthest from the-one with which wire 15 isconnected, should not be connected with the carbon. Hence when arm 8reaches this plate the light is extinguished.

The device is provided with two plates '10 and 17, one secured to thebase or plate 1 and the other connected with stem 2 and both connectedwith wire-cloth 18, thus forming a shield for the parts and at the sametime permitting free circulation of the air for the purpose of keepingthe mechanism at a sufii ciently-low temperature.

Having thus described I claim is 1. A rheostat consisting of aninsulatingblock 1, provided with aseries of plat-es 9, insulated fromeach other, metal screws 10, passing up through the block into saidplates, a carbon resistance supported upon block 1 and provided withclamps l4, surrounding the carbon,and securedby adj usting-screws 25,awire connecting each screw 10 with screw 25, a rdtating metal stem 2,secured to plate 1 and provided with a metal arm adapted to engageplates -9, and a circuit the wires of which are electrically connected,respectively, with stem 2 and the plate9 at one extremity of the semyinvention, what ries of plates, substantially as and for the purpose setforth.

2. A rheostat consisting of aninsulatingblock 1, provided with a seriesof metal plates 9, insulated from one another, metal screws 10, passingup through block 1 into said plates, a carbon resistance provided withadjustable clamps, wires connecting said clamps with screws 10, arotating metal stem 2, passing through block 1 and provided with ametal,

arm adapted to engage plates 9, a circuit the wires of which areelectrically connected, re: spectively, with stem 2 and the plate 9 atone extremity of the series, and a casing inclosing the mechanism andprovided with forami- Hated sides, substantially as and for the purposeset forth.

In testimony whereof I affix my signature in presence of two witnesses.

HARRY W. LAYVRENCE.

Witnesses: WM, McCoNNnLL, G. J. ROLLANDET;-

